A. The Malicious Software Removal Tool detects and removes high-profile viruses. The tool runs on all versions of Windows 2000 or later. This is not a real-time tool but rather an application you run periodically. You can obtain the tool via the Windows Update site; by default it will download, run in the background, then delete itself once a month. If you want to run the tool more frequently, download it here. Simply execute this file, called Windows-KB890830-ENU.exe, accept the license terms, and click Finish when the tool finishes running, as the figure shows. Remember, this tool doesn't connect to Microsoft to obtain new virus definitions each time it runs; the definitions are built into the tool. Therefore, it's important that you download the file every month when Microsoft releases a new version.